The present invention generally relates to systems and processes for treating eye disorders. More particularly, the present invention resides in systems and processes for preventing or treating myopia by applying pulsed energy to tissue of an eye having myopia or a risk of having myopia to provide treatment benefits while not permanently damaging the eye tissue.
Myopia is the condition known as “near-sightedness”, where the image in front of the eye is focused in front of the retina rather than exactly on the retina. This (focus of the image on the retina) is also referred to as “emmetropia”. The image in myopia may be focused in front of the retina for one or both of the following reasons: either the refractive strength of the front of the eye at the cornea and lens is excessive; and/or the axial length of the eye is too long, such that the retina is posterior to the image focal point, causing blurred vision. To counteract this visual blurring, those affected move closer to the object to be viewed. This moves the focal point of the image back and closer to the retina, causing the vision to become more clear.
Myopia is epidemic by usual medical definitions, affecting as many as 50% of adults, with increases in incidents in school-aged children in recent generations by 200% or more. This rapid increase and prevalence has been attributed to improved educational opportunities with increased usual activity, including reading time, as well as increased use of electronic devices and media.
The causes of typical myopia appear to be genetic and environmental. Higher education and greater time spent doing close work and reading are known to be risk factors for myopia. The stimulus for near work causing myopia suggests that this influences, possibly in part via accommodation of the crystalline lens, neurologic and/or chemical mediators of eye growth to increase the axial length of the eye. Evidence for this phenomenon is that paralyzation of accommodation with topical atropine in children is able to reduce the degree and incidence of acquired myopia.
The “emmetropic” factor or factors that promote normal eye growth and formation and axial length and that are diminished, blocked or inhibited by near work lead to an increase in eye length, most likely arise in the central retina or “macula” where visual images are normally focused. By hard-wired neurologic and/or diffusible chemical feedback mechanisms, auto regulation of ocular growth is disturbed to adapt the eye to the myopic focal point by encouraging actively, or allowing passively by loss of emmetropic stimulus, an increase in the axial length of the eye, increasing the condition of myopia.
Retinal dysfunction and alteration of retinal autoregulation in response to environmental factors is a common phenomenon and a common finding in most chronic progressive retinopathies, including age-related macular degeneration and diabetic retinopathy, ocular neurologic diseases such as chronic open angle glaucoma, and inherited retinopathies including retinitis pigmentosa and Stargardt's Disease. In glaucoma, a setting analogous to the development of myopia, selective complimentary sparing of visual field defects has demonstrated direct and neurologic and/or chemical communication between fellow eyes mediated by the central nervous system to minimize total visual disability. In response to high eye pressure in glaucoma, optic nerve tissue is sacrificed in such a way as to increase the probability of preserved visual field in one eye, covering lost visual field in the other eye, maximizing total visual function when both eyes are used together. Thus, there is a clear anatomic response mediated by retinal signaling which alters retinal and neurologic structure to accommodate the quality of visual stimuli and maximize visual function.
Pediatric myopia appears to develop and progress in the same manner and by similar mechanisms as other chronic progressive ocular diseases. An abnormal stimulus (chronic near-work and lens accommodation) causing alteration of retinal function and autoregulation in response to the abnormal environment, thus becomes abnormal and causes elongative growth to the eye to restore sharp near vision with less accommodative effort, and thus the condition of myopia develops.
Typical axial or refractive myopia can be corrected by glasses, contact lenses or refractive surgery. Its management costs the U.S. Healthcare System almost an estimated four billion dollars annually. Moreover, myopia is also often associated with reduced visual function and increases risks of vision loss due to retinal detachment, choroidal neovascularization, macular atrophy, and glaucoma. Together, the need for refractive correction of myopia, and medical consequences, constitute a significant public health problem and socioeconomic burden.
Accordingly, there is a continuing need for systems and methods which can prevent and/or treat the eye condition of myopia. Such a system or method should be able to modify biological factors that may contribute to acquired myopia, so as to slow or prevent acquired myopia. Such a system and method of treatment should be relatively easy to perform and harmless. The present invention fulfills these needs, and provides other related advantages.